Links with underscores
The URL strucure of a website must be simple. As Google mentioned, Googlebot favors dashes. To separate words using a dash is the correct way, because Googlebot does not count underscores as word separators. Replace underscores with dashes. Make sure that if you work with already indexed sites you can't simply change the characters. You have to redirect the underscored URL with a help of 301 redirect to a correctly used, dashed URL.
